1. Field of the Invention
The present invention relates generally to supercharging apparatus for internal combustion engines, and more specifically relates to apparatus for supercharging V-twin motorcycle engines.
2. Description of the Related Art
In the art of internal combustion engines, supercharging is a well-known technique for boosting an engine's performance. Currently, superchargers are either standard or optional equipment on common, consumer versions of a wide variety of motor vehicles. However, supercharging apparatus is not yet widely used on engines of certain consumer versions of motorcycles, the most notable being Harley-Davidson.RTM. motorcycles, virtually all of which include that company's distinctive V-twin engine design.
Past applications of supercharger technology to Harley-Davidson.RTM. V-twin engines have been primarily in the high performance and custom styling segments of the industry. Attempts to develop a consumer-acceptable version of a supercharger for O.E.M. or retro-fit applications have largely failed due to several primary drawbacks in previously-promoted designs. These drawbacks include: the necessity of uncomfortable modification of the rider's seating and/or leg position; unsightly alteration of the motorcycle's appearance; unacceptable alteration of the sound of the motorcycle; excessive complexity of design, requiring belts, pulleys, cables, and the like, and the tedious and continuous maintenance that such mechanisms demand; unreliability and short service life; a level of installation and/or maintenance difficulty beyond the likely skill and tool availability of the common consumer; a lack of means for easy modification of the performance of the unit; and, unacceptably high purchase and replacement part prices, as well as high costs of repair. One example of a motorcycle supercharger having some of these problems is that shown in U.S. Pat. No. 5,263,462 issued to Perry in 1993.
Superchargers are generally comprised of two primary portions, the blower portion and the transmission portion (not to be confused with the transmission in a vehicle's primary drive train). The blower portion is the supercharger's air compressing apparatus. The transmission portion delivers rotation from a power take-off on the engine to the supercharger's blower portion. Many of the above-identified problems can be attributed directly to the design of the transmission portions of such motorcycle superchargers. Indeed, superchargers for other types of motor vehicles wherein belts, pulleys and the like are employed in the transmission portion of the unit also suffer similar problems with respect to complexity, cost, service life, and repair.
Accordingly, it appears that a need exists for a supercharger which is easy and inexpensive to install in both O.E.M. and retro-fit applications, and which has a long, low-maintenance service life. And, for application to V-twin engine-powered motorcycles such as those manufactured by Harley-Davidson.RTM., it would be additionally beneficial if such a supercharger provided sufficient clearance for rider comfort, while not impairing two primary aesthetic features of which Harley-Davidson.RTM. owners are so fond, namely the motorcycle's sound and appearance. Yet further, it would be superiorly advantageous if such a supercharger were able to be easily modified to change its blower speed for higher performance applications.